A thermostat assembly is removably mounted in the engine block of every internal combustion engine. The well known conventional thermostat assemblies include a thermostatic element, a valve element, a valve seat and a biasing means to urge the valve element against the valve seat. The typical prior art thermostat assembly is shown in U.S. Pat. No. 3,153,933. Here, the thermostatic element contains a heat expandable material which expands when the temperature of the surrounding liquid exceeds a predetermined temperature. When the expansion of the thermostatic material in the thermostatic element takes place, the valve element is forced away from the valve seat.
Normally, when the surrounding liquid temperature falls below a preset value, the valve element is biased against the seat. This prior art thermostat assembly operates automatically with changing temperatures taking place in the surrounding coolant liquid. However, there are times when these thermostats fail to operate causing the valve element to stick in place to the valve seat. When this happens, the flow of coolant liquid is interrupted between the engine block and the radiator and causes overheating. Extensive damage is known to occur to the internal combustion engine under such overheating conditions.
This basic problem has been well recognized by the prior art and their have been several attempts to overcome this type of thermostat failure. Such prior art structures have been very complicated, costly and unable to satisfactorily meet the existing need. U.S. Pat. No. 3,776,457 discloses the use of a rubber or heat softenable material which softens when the temperature of the liquid exceeds a predetermined value. This type of structure is not easily controlled since it depends upon the temperature sensitivity of the chemical constituents in the plug material.
The U.S. Pat. No. 2,695,012 discloses an adjustable thermostat having a fairly complex structural configuration. The purpose of this prior art thermostat assembly is to establish a temperature differential between the lower and upper parts of the engine block. It is not possible to open the valve element permanently or to manually manipulate the thermostatic valve to provide a continuous flow of coolant liquid which will by-pass the thermostat completely.
The U.S. Pat. Nos. 2,833,478 and 2,750,117 disclose a thermostat assembly having a remote control capability. The control devices are located on the dashboard of the vehicle with the thermostat being placed in the normal location within the engine block. The complex nature of the assembly requires skilled personnel to install and maintain the effectiveness of the system.